A study of ultrastructural changes accompanying aging in Drosophila melanogaster is proposed. Particular attention is paid to those changes induced by beta-alanine incorporation into integumentary and supporting structures. The role of beta-alanine in coloring and compacting such structures is also explored with the fungus Morchella esculenta. As a far ranging objective, ultrastructural comparisons are made of juvenile and senescent connective tissues of mammals, with particular attention paid to changes induced by beta-alanine incorporation during aging. Electron microscope autoradiography, amino acid and, later, catecholamine analyses are made of these structures as well as hair of humans of various ages, hair and skin color phenotypes, and races.